         ; implementation
         exclude-lessons-on-empty-rows
         (fn [lessonInfoSeq]
-          (filter #(let [day   (:day %1)
-                         row   (:rowNum %1)
-                         ttRow (get-in Timetable [day row])]
-                     (not (empty? ttRow)))
+          (filter #(let [day    (:day %1)
+                         rowNum (:rowNum %1)]
+                     (timetable-row-not-empty? day rowNum))
                   lessonInfoSeq))
 
         sort-lesson-info-seq

            nil
            ttRow)))

(defn- create-lesson-div
  "Creates a <div> element for a new lesson using jQuery"
  [& {:keys [moduleCode moduleName lessonType lessonGroup venue slotsOcc

   Timetable, where 0 = Monday, 1 = Tuesday, until 4 = Friday."
  [day]
  (nth Timetable day))

(defn- timetable-get-day-row
  "Retrieves a row for a given day in `Timetable`."
  [day rowNum]
  (nth (timetable-get-day day) rowNum))

(defn- get-nr-rows-in-timetable-day
  "Returns the total number of rows in the given 0-indexed day in the Timetable,
